Browsing by Author "Reisig, Dominic Duane"
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- Diapause biology, dispersal capabilities and insecticide use for Lygus lineolaris in Mid-Atlantic cotton systemsSchepis, John Philip (Virginia Tech, 2024-06-03)Cotton (Gossypium hirsutum L.), is cultivated in the United States, primarily in regions characterized by long, hot summers to optimize plant growth. Virginia is the northernmost state where cotton is grown, with approximately 84,000 acres annually. The unique challenges of cultivating cotton in Virginia stems from its relatively short season due to its geographical location, lack of large contiguous acreage, and distinctive issues with pests. A significant pest of this region is the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), which emerged as a major threat to mid-Atlantic cotton during the late 2010s. L. lineolaris utilize a variety of wild and cultivated hosts to survive the winter months. The overwintering success and distribution of diapause survival L. lineolaris was measured on cover crops and weeds common in the Mid-Atlantic. Densities varied between weed and cultivated hosts, with L. lineolaris exhibiting increased survival in legumes compared to grains. Carbohydrate, lipid and protein levels were measured within diapausing and non-diapausing L. lineolaris specimens. Overwintering specimens usually had elevated level of carbohydrates and lipids, while containing decreased concentrations of protein. Nutrient quantification provided an effective tool in selecting for diapause status in L. lineolaris. Through the results from this study, an alternative method to dissection for determining diapause status in L. lineolaris has been identified. In the spring, movement of L. lineolaris throughout the landscape is highly dependent on host senesce. Flight analysis, behavioral assays and nutritional quantification assays on L. lineolaris populations from different weed hosts were performed to assess the flight capacity of specimens fed from different hosts. While weed hosts type provided populations with differing internal nutrient levels, sustained flight was not different between populations. When dispersal of L. lineolaris into cotton occurs, insecticide treatments following scouting are often necessary to prevent economic damage to the plant. Insecticide experiments were conducted aiming to assess the impact of different active ingredients on L. lineolaris, secondary pests, and natural enemy populations. Findings indicated that insecticides used to control L. lineolaris were successful at lowering pest populations and acephate was found to impact natural enemy populations. Plots applied with acephate experienced secondary pest outbreaks, highlighting the crucial role of natural enemies.
- Food webs and phenology models: evaluating the efficacy of ecologically based insect pest management in different agroecosystemsPhilips, Christopher Robin (Virginia Tech, 2013-09-02)Integrated pest management (IPM) is defined as an effective and environmentally sensitive approach to pest management that relies on a combination of common-sense practices. Integrated pest management programs use current, comprehensive information on the life cycles of pests and their interactions with host plants and the environment. This information, in combination with available pest control methods, is used to manage pest populations by the most economical means, and with the least possible hazard to people, property, and the environment. True IPM takes advantage of all appropriate pest management options including, as appropriate, the judicious use of pesticides. It is currently estimated the IPM in its full capacity is being practiced on less than ten percent of the agricultural land in the U.S. The primary objective of this research was to evaluate land management decisions and create new tools to promote a true IPM approach and encourage growers to reevaluate their method of insect control. To accomplish this I developed new predictive tools to reduce or eliminate unnecessary insecticide application intended to target cereal leaf beetle in wheat, and assessed a conservation biological control technique, farmscaping, to determine its true impact on lepidopteran pest suppression in collards.
- Influence of Selective Insecticides and Cropping System on Arthropod Natural Enemies in SoybeanWhalen, Rebecca Anne (Virginia Tech, 2016-06-28)Arthropod natural enemies play a key role in controlling potentially damaging pest populations in agroecosystems. An abundant and diverse natural enemy community is associated with higher yields in a variety of crops. Certain aspects of soybean production can make a field more or less amenable to a robust natural enemy community. For instance, commonly used broad-spectrum insecticides which are highly toxic to most arthropods can decrease natural enemy densities and allow for secondary pest outbreaks. Selective insecticides that have less impact on natural enemy populations allow for pest control while preserving important predators. Another production decision that could alter natural enemy communities is the choice of cropping system, specifically planting early (full season) or late, after small grain harvest (double crop). My research objectives were to examine how 1) selective insecticides and 2) cropping system affect the density and diversity of natural enemies in Virginia soybean. To address the first objective I compared the natural enemy community in soybean plots that were exposed to selective insecticides, broad-spectrum insecticides or no insecticide. I sampled insects using three different techniques and found that the two selective insecticides I tested, both from a new class called diamides, did not reduce the natural enemy community compared to controls. To examine how cropping system affects the natural enemy community I sampled full season and double crop fields during the growing season for two years. In 2014 ground-dwelling spider diversity was higher in full season soybean. In both years, double crop soybeans had higher abundance of spiders and insect natural enemies on the ground and in the foliage compared with full season soybean. This was unexpected, since double crop soybeans are planted later than full season and arthropod populations would have less time to colonize and grow. When I compared diversity of a family of predatory beetles I found higher diversity in full season soybean. The similarity in spider and insect natural enemy diversity and abundance trends suggests that a greater number of species can co-exist in full season soybean, while in double crop soybeans a few dominant natural enemies thrive.